Non‐technical summary  The enteric nervous system of the gastrointestinal tract regulates all the functions of the gut. Enteric neurons are surrounded and outnumbered by enteric glial cells, whose functions are not well understood. Digestive and defensive functions of the gut require the secretion of fluid into the lumen in a regulated manner. Fluid is controlled by the secretion or absorption of ions across the epithelium. Here we have identified a physiological role for enteric glia of the colon in the regulation of fluid balance, through the production of the gaseous mediator nitric oxide. Enteric glia work in concert with enteric nerves by using nitric oxide to regulate the movement of ions across the wall of the colon, thereby affecting water movement and hence digestion and host defence.